I would not be shocked to see a $2500 difference, BMW wants to steal customers from Audi and Mercedes (and others) so putting the premium too high wouldn't be a great strategy, plus thats basically $2500 extra profit compared to the F30, you can't tell me the F32 costs any more to make!
What I think will distinguish the F32 from the F30 and bring the price skyrocketing is the extra luxury options it will have that the "3 series" won't, like maybe nappa leather, LED lights, night vision... LED lights and Nappa/novillo leather could add $3K alone. You can get a F30 xdrive for around $62K right now if you tick every box, I bet the F32 will be close to $70K if you tick every box, of course it would have more features.
I just hope the GC isn't priced too high above the coupe or F30. I think there are plenty of people willing to pay for a 6 GC and pay the premium but people who buy 3 & 5 series (and now 4 series) care about value a lot more, I don't see anyone willing to spend $6K more for a 4 GC over a 3 sedan with the same options.